1. Field of the Invention
The present invention relates generally to a semiconductor device, and more particularly, to a method for repairing a semiconductor device.
Generally, as semiconductor devices become highly integrated, in case of DRAM, the size of the chip increases while memory capacity increases.
2. Description of Related Technology
If even one memory cell among numerous micro memory cells of a semiconductor device has a defect as a result of the fabrication of the semiconductor device, the whole device is regarded as being defective and is discarded, thereby reducing device yield.
To overcome this problem, presently, the semiconductor device is designed with redundancy cells, which are formed in advance. A defective cell may be replaced with a redundancy cell, resulting in repair of the whole memory, and thereby improving (or not reducing) yield.
The repair operation with a redundancy cell is performed to identify a defective memory cell through a test after wafer processing and to replace the corresponding address of the defective memory cell with an address signal of a spare cell. When an address signal corresponding to a defective line is inputted, the defective line is substituted by a redundancy line.
FIG. 1 is a diagram illustrating a conventional semiconductor device. View (a) is a plane diagram illustrating a semiconductor device, and view (b) is a cross-sectional diagram taken along line A-A′ of (a).
Referring to FIG. 1, a first interlayer insulating film 12 is formed on an upper portion of a semiconductor substrate 10 having a lower structure (not shown). A line type fuse 14 is formed on an upper portion of the first interlayer insulating film 12. Here, the fuse 14 has a structure on which a barrier metal layer 14a, a conductive layer 14b and an anti-reflection layer 14c are stacked. The barrier metal layer 14a and the anti-reflection layer 14c are preferably formed with a stacked structure of a Ti film and a TiN film, respectively.
The conductive layer 14b is preferably formed with the same material as a metal wiring of a cell region, for example, aluminum (Al). A fuse blowing target 16 indicates a target area to which a laser is irradiated in a blowing process. A second interlayer insulating film 18 is formed on the whole surface of the semiconductor substrate 10 in which the fuse 14 is formed.
FIG. 2 is a diagram illustrating a method of repairing of the semiconductor device illustrated in FIG. 1.
Referring to FIG. 2, a conventional blowing process irradiates a laser into the fuse 14 corresponding to a defective cell to cut. However, a crack can be generated in the first interlayer insulating film 12 due to a laser energy in the blowing process.
A residue B of the conductive layer 14c or the barrier metal layer 14a can remain in a place where the crack is generated, such that it can not be determined that the fuse 14 is cut, even in case of cutting.
Accordingly, there is a problem of generating device failure as a repair of the defective cell is not successfully performed. Moreover, the blowing process using a laser energy performs cutting by melting, vaporizing, or exploding the fuse 14 such that it can have an associated problem of generating device failure due to the damage of the adjacent fuse 14.